The subject matter disclosed herein relates generally to imaging systems, and more particularly to a method and apparatus for optimizing data selected to reconstruct a Positron Emission Tomography (PET) image.
Multi-modality imaging systems exist that scan using different modalities, for example, PET and Single Photon Emission Computed Tomography (SPECT). During operation, the image quality of the conventional imaging systems may be affected by the motion of the object being imaged. More specifically, imaging artifacts may be produced by movement of the object during image acquisition. Respiratory motion is a common source of involuntary motion in mammals (e.g., people and animals) encountered in medical imaging systems and therefore is also a common source of the imaging artifacts.
One known method for reducing the imaging artifacts is to sort the image data into a plurality of bins. One of the bins is then selected as the reference bin and the remaining bins are then registered to the reference bin. However, the reference bin may not include optimal information for registering the remaining bins. For example, the reference bin may include a fewer number of pixels or pixels having a reduced pixel intensity. Thus, when the remaining bins are registered with the reference bin, the quality of the resultant image may be reduced.
Additionally, a PET imaging procedure may last 2-3 minutes per acquired data at a bed position. Thus, several respiratory cycles of image data are acquired and sorted to contribute to image data for each bin. In general, it is assumed that the respiratory cycles include image data that is repeating for the internal patient anatomy over the respiratory cycles such that image data for each respiratory cycle may be summed into the bins. However, in general the patient's breathing is not consistent over the entire imaging procedure. The methods described herein may be applied independently to any or all such data acquisitions associated with a multi-position (‘whole body’) scan where respiratory motion is present.
In some methods for reducing the imaging artifacts, the patient may hold their breath during the scan. However, because PET data, for example, may be acquired over several minutes, the patient typically has to breathe several times during the PET acquisition. Thus the patient's breathing results in patient motion which may potentially result in imaging artifacts.